This invention relates in general to the construction of roof-supporting shield structures and, in particular, to a new and useful supporting shield structure for use in an excavation, such as a mine, which includes a shield member disposed at an angle in respect to a sill skid which is movable along the mine floor and which pivotally supports at its upper end a roof cap lever having a crank arm which is connected to a fluid motor for the purpose of shifting the roof cap into association with the roof.